Rabbit Anti-Human HLA E (a.a. 251-358) Polyclonal antibody

In our previous studies, we have shown that patients with serous ovarian carcinoma in advanced surgical stage disease have a particularly poor prognosis if they carry the HLA-A*02 genotype. This represent a stronger prognostic factor than loss or downregulation of the MHC class I heavy chain (HC) on tumor cells. In this study, we investigated the expression of the non-classical, immune tolerogenic HLA -G and -E on the tumor cells along with the infiltration of immune cells in the tumor microenvironment. FFPE primary tumors from 72 patients with advanced stages of serous adenocarcinoma and metastatic cells present in ascites fluid from 8 additional patients were included in this study. Both expression of HLA-G and aberrant expression of HLA-E were correlated to a significant worse prognosis in patients with HLA-A*02, but not with different HLA genotypes. Focal cell expression of HLA-G correlated to a site-specific downregulation of classical MHC class I HC products and aberrant HLA-E expression, showing a poor survival. HLA-G was more frequently expressed in metastatic cells than in primary tumor lesions and the expression of HLA-G inversely correlated with the frequency of tumor infiltrating immune cells. All these parameters can contribute together to identify and discriminate subpopulations of patients with extremely poor prognosis and can give them the opportunity to receive, and benefit of individually tailored treatments.

BackgroundIn pig-to-human xenotransplantation, early cellular rejection reactions are mediated by natural killer cells (NK cells). Human NK cells are inhibited by HLA-E via CD94/NKG2A receptors. To protect porcine grafts against human NK cell responses, transgenic GTKO pigs expressing hCD46 and HLA-E have been generated. The aim of this study was to test the effect of this genetic modification on xenogeneic, and in particular human NK cell response, using an ex vivo perfusion model of pig hearts with human blood. MethodsCardiopleged and explanted genetically modified (gm) pig hearts (GTKO/hCD46/HLA-E/h2-microglobulin) and wild-type (wt) controls (n=6 each) were reperfused and tested in an 8hours ex vivo perfusion system using freshly drawn human blood. Cardiac function was evaluated during a 165-minute period in working heart mode. Myocardial damage, antibody deposition, complement activation, and coagulation parameters were evaluated histologically at the end of perfusion. The number of NK cells in the perfusate was determined by flow cytometry at baseline and at 8hours; tissue infiltration by NK cells was quantified by immunofluorescence microscopy using NKp46 staining of frozen sections. ResultsDeposition of IgG (1.21x10(7) vs 8.8 +/- 2.9x10(6); P<.01), IgM (4.4 +/- 3.7x10(6) vs 1.7 +/- 1.2x10(6); P<.01), and the complement activation product C4b/c (3.5 +/- 1.3x10(6) vs 2.3x10(6)+/- 9.4x10(5); P>.01) was lower in gm than wt hearts. NK cell percentages of leukocytes in the perfusate decreased from 0.94 +/- 0.77% to 0.21 +/- 0.25% (P=.04) during xenoperfusion of wt hearts. In contrast, the ratio of NK cells did not decrease significantly in the gm hearts. In this group, NK cell myocardial infiltration after 480minutes of perfusion was lower than in wt organs (2.5 +/- 3.7x10(4)/mm(3) vs 1.3 +/- 1.4x10(5)/mm(3); P=.0001). The function of gm hearts was better preserved compared to wt organs, as demonstrated by higher cardiac index during the first 2hours of ex vivo perfusion. ConclusionGTKO, hCD46, and HLA-E expression in porcine hearts reduced complement deposition, complement dependent injury, and myocardial NK cell infiltration during perfusion with human blood. This tested combination of genetic modifications may minimize damage from acute human-anti-pig rejection reactions and improve myocardial function after xenotransplantation.